linux-kernel - Re: [RFC PATCH] getvalues(2) prototype

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Message-ID: <YjwQ4dLH7BWOqZqr@infradead.org>
Date:   Wed, 23 Mar 2022 23:34:09 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Miklos Szeredi <miklos@...redi.hu>,
        Christian Brauner <brauner@...nel.org>,
        Miklos Szeredi <mszeredi@...hat.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Linux API <linux-api@...r.kernel.org>,
        linux-man <linux-man@...r.kernel.org>,
        LSM <linux-security-module@...r.kernel.org>,
        Karel Zak <kzak@...hat.com>, Ian Kent <raven@...maw.net>,
        David Howells <dhowells@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <christian@...uner.io>,
        Amir Goldstein <amir73il@...il.com>,
        James Bottomley <James.Bottomley@...senpartnership.com>
Subject: Re: [RFC PATCH] getvalues(2) prototype

On Wed, Mar 23, 2022 at 06:19:51PM -0400, Theodore Ts'o wrote:
> I'm still a bit puzzled about the reason for getvalues(2) beyond,
> "reduce the number of system calls".  Is this a performance argument?
> If so, have you benchmarked lsof using this new interface?

Yeah.  Even if open + read + close is a bnottle neck for fuse or
network file systems I think a io_uring op for just that is a much
better choice instead of this crazy multi-value operation.

And even on that I need to be sold first.